Experimental Study on the Mechanical Endurance of Vacuum Interrupter Bellows Subjected to High Gas Pressure and High Opening Velocity

When a vacuum interrupter (VI) is used in a high pressure of insulating gas with a high opening velocity, a high electrical insulation level can be achieved. However, it will increase the risk of the bellows fatigue failure after a number of mechanical operations. Through empirical formulas and simulation calculation, one can get the stress and mechanical endurance of the vacuum interrupter bellows, however, there is no experiments revealing the mechanical endurance of the bellows when it is subjected to high gas pressure and high opening velocity. The objective of this paper is to experimentally determine the mechanical endurance of the VI bellows subjected to high gas pressure and high opening velocity. A 40.5 kV electromagnetic repulsion actuator is used to drive a bellows component to achieve a high velocity, and a semi-sealed tank is used as the gas pressure regulating unit. Two cases were experimentally investigated, in which the inner surface and the outer surface of the bellows suffered the high gas pressure, respectively. In the first case, the gas pressure subjected to the inner surface was 0.5MPa, and that of the outer surface was 0.1 MPa, respectively, the opening velocity was 2.8 m/s. In the second case, the gas pressure subjected to the inner surface was 0.1MPa, and that of the outer surface was 0.6 MPa, respectively. The opening velocity was 3.5 m/s, 5 m/s and 6.5 m/s, respectively. The experiments results showed that the mechanical endurance of the first case was 1410 cycles. The mechanical endurance of the second case was 705, 437, and 288 cycles when the opening velocity was 3.5, 5 and 6.5 m/s, respectively.